Drive mechanism



April 30, 1963 c. KRoLl. ETAL 3,087,346

DRIVE MECHANISM Original Filed Jan. 29, 1957 4 3116915-51166?, 1

INVENTORS Corne Las Km Aqlzwnan/MKPOM ATTORN EYS April 30, 1963 c. KRoLl. ETAL 3,087,346

DRIVE MECHANISM Original Filed Jan. 29, 1957 4 Sheets-Sheet 3 ATTORNEYS April 30, 1963 c. KROLI. ETAL 3,087,346

DRIVE MECHANISM Original Filed Jan. 29, 1957 4 Sheets-Sheet 4 ,INVENTORs Connelzas Know NofwzanMKroZ ATTO R N EYS United @rates This invention relates to the art of drive mechanisms which are particularly adapted for use with transferring apparatus and more particularly to apparatus for parking automobiles.

Where automobiles are parked in vertically aligned stalls or on platforms by means of an elevator 4having a conveyor on which the Vehicle is initially positioned and which elevator is moved vertically into substantial alignment with such stalls so that the conveyor may thereon be moved transversely into the stall to deposit the automobile therein and Where the supporting structure for the stall necessitates he-avy beams that require bulky supports that occupy considerable vertical space, the overall height of the installation will be increased, with resultant increase in cost thereof.

It is accordingly among the objects of lthe invention to provide an installation of the above type that is relatively simple in construction and dependable in operation, which will accommodate a relatively large number of vehicles in a minimum of space and will, with the use of a relatively simple control and drive system, provide -automatic and rapid parking of automobiles, without need for an attendant in the vehicle or the need for manual chocking of the vehicle or locking of its brakes, and Without the need for jacks or the like to raise the weight of the automobile oif its wheels, or the need for ramps and heavy floors, ceilings and walls found in conventional garage structures, and which will yalso provide automatic and rapid return of parked automobiles to the customers.

These objects are accomplished hy the arrangement and combination of elements hereinafter described and more particularly recited in the claims.

This application is a division of `co-pending application Serial No. 636,995, tiled January 29, 1957, now Patent No. 2,945,602, dated July 19, 1960.

In the accompanying drawings in which are shown one or more of various possible embodiments of the several features of the invention,

FIG. 1 is a plan View of the drive mechanism and associated conveyor,

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1,

' FIG. 3 is a sectional view taken along line 3--3 of FIG. 4,

FIG. 4 is a top plan view with parts broken away of the crank bar,

FIG. 5 is a perspective view on an enlarged scale of a portion of the locking mechanism,

FIG. 6 is a view similar to FIG. 5 on a smaller scale of another portion of the locking mechanism,

FIG. 7 is a top plan view of the drive mechanism according to another embodiment of the invention,

IFIG. 8 is a sectional view taken along line 8 8 of FIG. 7,

v FIG. 9 is a view similar to lFIG. 8 taken along line 9-9 of FIG. 7,

FIG. l0 is a perspective view of the locking ring member of the embodiment shown in FIG. 7,

FIG. 11 is a perspective view of the worm gear,

FIG. 12 is a fragmentary perspective view of the crank bar of the embodiment of FIG. 7 in another position.

The drive mechanism which is illustratively shown arent rice in FIGS. l and 2 incorporated in an automobile transferring apparatus of the type shown in Patent No. 2,945,- 602, comprises a housing '71 mounted on a rigid member 24, said housing having a vertical shaft 72 rising therefrom. Positioned between the top and bottom walls 73 and 74 of the housing is a worm gear 75 engaged by a worm 76 driven by a motor M also mounted on floor 24. The ygear is keyed to said shaft 72 as at 77, and the housing 71 desirably has bushings 78 and 79 rigid -therewith through which the shaft extends. Afixed to lbushing 79 (FIG. `2) above the top Wall 73 of the housing is a gear 81, said shaft 72 extending beyond said ygear 81 and mounting a crank member 82 thereon. As shown in FIG. 4, the crank member comprises an elongated bar having a central opening 83 through which the upper end of the shaft 72 extends, said shaft being keyed to said bar. Each of the ends 84, 85 of the bar has a pair of spaced laterally projecting iingers 86 and 87 which define an arcuate slot 88, 89 therebetween, the outermost finger `86 being of shorter length than the innermost finger 87. The ends of Aboth of said fingers extend to a line which is the circumference of a circle having the axis of shaft 72 as its center.

The drive mechanism is designed to effect movement of a substantially rectangular frame 65 which comprises a pair of spaced parallel cross beams 66, 67 formed from inverted U-shaped. members. The ends of the cross beams which are closed, are formed by parallel beams 68 and the cross beams are secured as by brackets 69 to sections A and 1B of a conveyor 32 of the type shown in said Patent No. 2,945,602 so that the sections A and B and frame 65 form an integral unit.

Each of the sections A and B of the conveyor 32 is designed to slide between an associated pair of tracks 31 as shown in FIG. 4 when the drive mechanism is actuated.

As the conveyor is clearly shown and described in said Patent No. 2,945,602, it will not be further described.

As shown in FIGS. 2 and 3, the crank bar 82V is positioned in a plane below that of the cross beams 66, 67 and in the neutral position of the crank bar, as shown in FIGS. l and 4, the closed ends 91, 92 of each of the `slots 88 and 89 are aligned with the associated cross beams 66 'and 67.

The gear 81 which is fixed with respect to the housing 71 meshes with a pair of idler gears 93 and 94 rotatably mounted on stud shafts 95 depending from the crank bar 82 on each side of central opening 83 therethrough. The idler gears y93 and 94 mesh respectively with gears -96 and 97, illustratively of smaller diameter than gears 93, 94, each of said gears 96, 97 serving to operate a locking member 98, 99 shown in FIGS. 3 and 5. The locking member comprises a disc 101 having a radial arcuate notch 102 therethrough and having a stem 103 to the lower end of which an associated gear 96 and 97 is aiixed.

Means are provided rotatably to mount the locking members on the crank bar 82. To this end, for example, referring to the locking member 98 which is substantially identical to member 99, the crank bar 8-2 on its undersurface, concentric with the rear end of arcuate slot `88, has a substantially arcuate recess 104 therein in which the disc 101 is positioned. An annular housing 105 `(FIG. 6) with an inwardly extending flange 106 at its lower edge is secured as by screws 107 to the undersurface of the crank 4bar coaxial with the arcuate recess 104 therein. The housing 105 has a cutout 108 therethrough and the radial arcuate notch 102 in the disc `101 may be moved into alignment with such cutout in the manner hereinafter to be described. The housing 105 serves as a bearing for the disc 101 so that it is free to rotate.

Extending into the central portion of each of the discs 101 through the ends -of arcuate slots 88, 89 in crank bar 82 is a heavy pin 111 of strong rigid material such as steel. The upper end of each of the pins has a head 112 and a bearing 113 encompasses said pin adjacent its upper end as is clearly shown in FIG. 3. The outer race of the bearing 113 is positioned in a roller 114 which has an inwardly extending ange at its lower end to support the outer race of the bearing, said outer race and said roller desirably being secured as by force t. The roller on its outer periphery has spaced flanges 115 which straddle an elongated rail 116 aixed to the side walls 117 of the cross beams 66, 67 and extending the length thereof.

As shown in FIG. 1, each of the cross bars has a stop member 121 which is adjacent the roller 114 when the latter is in the neutral position shown, to limit movement of said roller to the right. In addition, the oor 24 mounts a curved upstanding guide plate 122 having its inner end adjacent the pin 111 and clear of the latter and its outer end adjacent the side edges 123 of the floor 24 and aligned with the left ends of the cross beams 66, 67.

In the operation of the equipment, the drive motor M is energized. As a result, the worm 76 thereof will rotate worm gear 75 in, say, a counterclockwise direction from the position shown in FIG. l to effect rotation of the shaft 72 and crank bar 82 thereon in a similar direction. As the shaft 72 is rotated in a counterclockwise direction, the gears 96 and 97 will rotate in a clockwise direction (FIG. 4) by reason of the drive imparted thereto from the fixed gear 81 through the idler gears 93, 94.

Referring to FIG. 4, as the end 84 of the crank bar 82 moves in a counterclockwise direction, the end 91 of arcuate slot 88 will engage the pin 111 to move the latter in a circular path along beam 66. At the same time, by reason of the rotation of gear 96, the disc 101 of locking member 98 will be rotated in a clockwise direction so that the notch 102 therein will be moved further out of alignment with the arcuate slot 8S to retain the pin 111 locked in such slot. The movement of the pin 111 in a counterclockwise direction will cause the latter, through the roller 114 thereon, to react against the cross beam 66, moving the frame 65 in a downward direction from the position shown in FIG. 1.

Due to such rotation of the shaft 72, the end 85 of the crank bar 82 shown in FIG. 4 will also move in a counterclockwise direction so that the closed end 92 of the arcuate slot 89 will move away from the associated pin 111. Inasmuch as the gear 97 of locking member 99 is moving in a clockwise direction, the notch 102 in disc 101 of locking member 99 will move into alignment with arcuate slot 89 to release the associated pin 111 through opening 108 in housing 105.

As the frame 65 moves downwardly from the position shown in FIGS. 1 and 4, it is apparent that the pin 111 associated with the end 85 of crank bar 82, which is retained in the cross beam 67, will also move downwardly, the curve of the arcuate slot 89 permitting such movement of the pin which has been released from the .associated locking member 99 by the rotation of the disc 2101.

With continued rotation of the crank bar, the rate of travel of the frame 65 will increase rapidly and cofrrespondingly decrease when the crank bar has made 180 degree rotation. Thus, there will be little movement imparted to the frame at the beginning and end of such 180 degree travel. When the crank bar 82 has completed such 180 degree movement by reason of the drive imparted to the gear 96, the disc 101 of locking member 98 will have rotated suciently to completely lock the associated pin 111 with respect to the crank bar 82, and the pin 111 associated with locking member 99 will have been completely released and will have movedrdownwardly from the position shown in FIG. 1, completely clear of crank bar 82 so that it is located in cross beam 67 somewhere between the stop 121 carried thereby and the guide plate 122.

Due to such movement of the frame, as above described, by reason of the rigid connection of the cross beams 66, 67 to the beams 33, the sections A and B', will be moved downwardly from the position shown n FIG. l.

To move the sections A and B in the opposite direction, the motor M is energized in reverse direction so that the shaft 72 driven thereby will rotate in a clockwise direction, as will the crank bar 82. As the result of such movement, inasmuch as the disc 101 of locking member 98 associated with beam 66 has been rotated by gear 96 to fully lock the associated pin 111, the clockwise rotation of the crank bar will cause the disc 101 to react against the pin 1-11 to move the latter also in a clockwise direction, thereby moving the frame 65 in an upward direction, as shown in FIG. 1. This movement 0f the -frame is also sinusoidal in effect, being relatively slow at the beginning and end of the 180 degree rotation of the crank bar 82. As the frame moves, the gear 96 will be rotated by the drive previously described, but the associated disc 101, though tending to move from locked toward unlocked position, will remain locked even when it is restored to the neutral position shown in FIG. l. As the frame moves upwardly to the position shown in FIG. l the pin 111 carried by the cross beam 67 will abut against the guide plate 122 and be cammed toward the stop 121. The pin 111, during the course of such movement, will enter the arcuate slot 89 in crank bar 82 and be `guided thereby through the opening 108 in housing and through the notch 102 in ydisc 101, which will have been moved into alignment with the arcuate slot, against the end 92 of such slot, and thereupon, when the crank bar 82 has been moved to neutral position, the associated pin 111 will also be locked by further rotation of the disc 101 of locking member 99.

Instead of the drive means shown in FIGS. 3 and 4, for example, the drive means shown in FIGS. 7 to 11 may be used, parts corresponding to those in FIGS. 3 and 4 having the `same reference numerals primed.

IReferring to FIG. 7, the frame 65 also is substantially rectangular, having parallel cross beams 66 and 67 connected by parallel members 68', the ends of the cross beams `66' and 67' being connected to sections A' and B to form an integral unit.

Aixed as by welding, as shown in FIG. 8, to the cross beams 66', 67 respectively, are cross heads 151 and 152, illustratively inverted U-shaped members. The members 151 and 152 extend from the left member 68', terminating short of the right member 68', as is clearly shown in FIG. 9. The opposed inner walls 153 of members 151 and 152 taper inwardly as at 154 and each has .an opening 155 therethrough clearly shown in FIG. 9, the purpose of which will be hereinafter described.

Mounted on the Hoor 24" and lcentrally positioned thereon is a housing 71 which has a vertical shaft 72 rising therefrom. Afxed to shaft 72 as by keying at 77' is a worm gear 75 engaged by a worm 76 driven by a motor (not shown) also mounted on the iioor 24. The housing 71 desirably has bushings 78 and 79 rigid therewith through which the shaft 72 extends, suitable bearings 157 being positioned in said bushings rotatably to mount the shaft 72. iIdly mounted on the shaft 72 between the bushings 78' and 79' is a stop ring member 158 which has an arcuate notch 159 in its periphery, illustratively occupying 100 degrees of arc. The worm lgear 75 has on its upper surface a dog 161 which may travel.

is a crank bar 82', the latter having a central opening 83' therein through which the shaft 72 extends, said crank bar 82 being secured to the shaft 72 as by keying. The crank bar 82 is so positioned on the shaft 72 that it will extend at right angles to the center line of the dog 161 rigid with the worm gear 75, as is clearly shown in FIG. 7. With the crank bar 82' so positioned, it will also extend at right angles to a dog 164 aflixed as by welding to the bushing 79 and diametrically opposed to the dog 161 on the gear 75. The dog 164 on the bushing 79 also occupies 3() degrees of arc, as does a dog 165 axed to the ring member 158 midway between the ends of arcuate notch 159.

Each of the ends 84 and 85 of the crank bar 82' has an opening in which is aflixed an upstanding pin 167, the upper end of which illustratively mounts a roller 168 which is positioned between the inner and outer walls 153, 168 of each of the cross heads 151, 152, as is clearly shown in FIG. 8. l

In the operation of the equipment with the drive means shown in FIGS. 7 to l1, the worm 76 is driven by the associated drive motor (not shown) to rotate worm gear 75 in, say, a counterclockwise direction from the position shown in FIG. 7. This will cause rotation of the shaft 72 and the crank bar 82 thereon in a similar direction. As the shaft 72 is rotated in a counterclockwise direction, the pin 167 at the end 84 of crank bar l81V will react against the side wall 153 of cross head 151, tending to move the frame 65' in a downward direction from the position shown in FIG. 7. As the frame 65 moves downwardly, inasmuch as the end 85 of the crank bar 82 will also move in a counterclockwise direction, the pin 167 carried thereby will be guided by the curved portion 154 of the side wall 153 of cross head 152 through opening 155 in wall 153 so that such pin is clear of said cross head.

With continued rotation of the crank bar 82', the rate of travel of the frame 65 will increase rapidly and correspondingly decrease when the crank bar has made- 180 degree rotation to effectively provide a sinusoidal rate of travel. Thus, there 'will ybe little movement imparted to the frame at the beginning and end of such 180 degree As the crank bar 82 moves through a 180 degree arc, by reason of the downward movement of the frame 65' from the position shown in FIG. 7, the pin 167 at the end 85 of the crank bar 82 will pass through the space 170 defined between the end 180 of the cross head 151 and the right member 68 so that it is completely clear of the cross head 151.

Due to such movement of the frame 65 as above described, by reason of the rigid connection of the cross beams 66 and 67 `to the sections A and B the latter will be moved downwardly.

When the crank bar 82 is rotated 180 degrees from the position shown in FIG. 7, a limit switch may -be provided to de-energize the motor driving shaft 72. As the rate of movement of the frame 65 at such time is extremely slight, there would be little chance for the crank bar 82 to move further than 180 degrees, and even if there was any slight additional travel of the crank bar 82 this would have no harmful effect, as it only tends to retract the conveyor slightly from its fully extended position.

In the remote contingency that the limit switch (not shown) should cut off erroneously when the pin 167 at the end 84 of crank bar 82 was aligned with opening 155 in cross head 151, which would be in a position several degrees further in a counterclockwise direction from that illustratively shown in FIG. 12, due to the inertia tending to move the frame 65' upwardly at such time due to such overtravel, the frame 65 may move past the pin 167 so that both of the pins 167 would be clear of the associated cross heads, rather than the single pin 167 associated with cross head 152. which is required. In such a contingency, the equipment would have to be 6 manually reset. To prevent this overtravel, which is unlikely, the dogs 161, 164 and 165 and lthe stop ring member 158 are provided.

Thus, referring to FIG. 7, when the crank bar 82 ini-tially starts its movement, the dog 161 carried by worm gear 75' will abut against the end 191 of the arcuate notch 159, thereupon causing the ring member 158l to rotate in a counterclockwise `direction from the position `shown in FIG. 7.

As the dog 164 mounted on the bushing 79' afiixed to the housing is initially diametrically opposed to the dog 161 carried by the worm gear 75, as previously described, and as both of such dogs occupy 30 degrees of arc, it is apparent that the leading edge 192 of dog 161 twhich engages the end 191 of the arcuate notch 159, which occupies i degrees of arc, wi-ll become aligned with the edge i193 of the dog 164 aixed to the bushing when the worm gear 75 has rotated 150 degrees. Inasmuch as the arcuate notch 159 occupies 100 degrees of arc and the dog 165 carried by the ring member 158 occupies 30 degrees of arc, the edge 191 of the notch 159 is spaced from the edge 194 of dog 165 by an angle of 35 degrees. Consequently, the worm gear 75 will be able to rotate 35 `degrees further before the dog 165 abuts against the fixed dog 164 `to restrain further rotation of the worm gear 75.

This restraint `of movement after ,185 degrees rotation of the crank bar 82 will prevent movement of the pin 167 carried by end 84 thereof -to a position in which it is in alignment with the opening in cross head 151. Hence, there is no likelihood of sufcient over-travel of the frame 65' as previously described to cause the pin 167 carried by end y84 of crank bar 82 to be moved out of the cross head 151, which would interfere with subsequent operation of the equipment and require manual resetting thereon.

To move the sections A and B in the `opposite direction, the motor driving shaft 72 is energized in reverse ydirection so that the shaft 72 will rotate in a clockwise direction, `as will the crank bar 82. As .the result of such movement, inasmuch as the pin 167 carried by the end S4 of the crank bar `82 is still between the walls 153V and 16S of the cross head 151, it will react against the wall 16S, tending -to move the frame in an upward direction from the position shown in FIG. l2. This movement of the frame is also sinusoidal in effect, being relatively slow at the beginning and end of the `18() degree rotation of the crank bar 82. As the frame 65 moves upwardly, the pin 167 carried by the end 85 of the crank bar 82 will move through the opening 17) between the end of the cross head 151 and the right cross member 63 and through opening 155 in wall 153 of cross head 152 to again be positioned between the side walls 153 and 168 of cross head 152, as shown in FIG. 7.

When the worm gear moves in a clockwise direction, it will also move l5() degrees before the edge 192 of dog 161 thereon is aligned with the edge 193 of dog 164 laffixed to the bushing 79. Thereupon, the ring member y15S will move 35 degrees additionally before the dog 165 thereon abuts against dog 164 to restrain further movement `of the worm gear 75 to prevent the pin 167 at end 8'5 of crank bar 82" moving c-lear of cross head 152, as previously described with respect to cross head 151.

By reason of the bi-sinusoidal movement imparted to the frame by the drive mechanism above described, the drive mechanism may be relatively compact, thereby cutting -down the size of the installation and, in addition, as the conveyor, when retracted, will have very little speed, it is not likely to overshoot its central position. If desired, a relatively simple brake mechanism could be used to immediately restrain rotation of the shaft 72 or '72 upon de-energization of the associated motor M, for, since the rate of movement of the frame is relatively slow at such time, little braking effect is required. The bisinusoidal arrangement inherently provides both a braking action and a static brake.

As many changes could be made in the above equipment, and many `apparently widely different embodiments of this invention could be made without departing from the scope of the claims, it is in-tended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

l. Drive means comprising a pair of spaced parallel rigidly connected beams forming a frame member, means slidably mounting said frame member, :a drive shaft extending at right angles to the plane -of said frame member, a crank bar member centrally mounted on said shaft and extending at righ-t :angles thereto, a pair of drive pins carried by one of said members and positioned to coact with the other of said members and means to effect positive reaction of one of said pins against one of the parallel members of said frame upon rotation of said drive shaft .and movement of said crank bar member from a position at right angles to said parallel member of said frame whereby said frame will be moved along its slidable mount.

2. Drive means comprising a pair of spaced parallel rigidly connected members forming a frame member, means slidably mounting said frame member, a drive shaft at right angles to the plane of said frame member, a crank bar centrally mounted on said shaft at right angles thereto, a pair of pins depending respectively from said parallel members and mounted thereon for slidable movement 'longitudinally thereof, said crank bar 4at each end having an elongated arcuate slot extending substantially at right angles to the length thereof and curved toward each other, both of "said pins, when said crank bar extends at right angles to said parallel members and parallel to the plane f `said frame member, extending through an associated slot lat the inner end thereof, means to lock said pins in the associated slots and means controlled by the rotation of said drive shaft and said crank bar to lock one =of said pins in the associated slot Vand to effect the release of the other of said pins for movement of the associated arcuate slot clear of said other pin.

3. The combination set forth in claim 2 in which a gear is mounted coaxial with said shaft and ixed so that it is restrained from rotation, a pair of gears is rotatably mounted on said crank bar on each side of the shaft and mesh with said iixed gear, said locking means comprises a pair of discs rotatably mounted on said crank bar at the respective ends thereof, each of said discs having a bore therein in which .the end of an associated pin is positioned and an arcuate notch leading into said bore at right angles thereto, one of said notches being curved in direction opposed to the -associated arcuate slot in the crank bar and the other curved in the same direction as the associ-ated arcuate slot in the crank bar, and a gear rigid with each of said discs and meshing respectively with said pair of gears, whereby upon rotation of said cnank bar [both of said lgears will ibe rotated in the same direction so that rotation of one of the discs will move the arcuate notch therein out lof alignment with the associated arcuate slot in the crank bar to lock the associated pin therein and rotation of the other disc will move the arcuate notch therein into alignment with the associated arcuate slot in the crank bar so that the latter may move clear of the associated pin.

4. Drive means comprising Ea pair of spaced parallel members slidably mounted for movement in unison, a

drive shaft at right angles to the plane of said members, a crank bar centrally mounted on said shaft at right angles lthereto, a pair of pins aflixed respectively to each end of said cr-ank bar and extending .at right angles thereto, said spaced parallel members each having an outer and an inner depending wall extending from one end of the associated member, said p-ins when the `crank ybar extends at right angles -to said parallel member being positioned between the associated inner and outer walls, each of said inner wall-s having -an opening through which the associated pin is adapted to pass, whereby upon ro-tation of said shaft one of said pins will react against the associated inner wall to effect slidab'le movement of said parallel members and the other pin will move out of said opening clear of the `associated member.

5. ",[lhe cornination set forth in claim 4 in which means a-re provided to `limit the rotation of said crank bar by said shaft.

6. The combination set forth in claim 4 in which a disc is coaxial with said shaft and is idly mounted thereon, said disc having an arcuate notch in its periphery and a projection rigid therewith between the ends of said slot and extending at right angles Ito the plane of said disc, a drive gear is affixed to s-aid shaft to rotate the latter, said gear having a projection extending at right langles to the plane thereof and positioned in said arcuate notch, and a fixed stop member is provided in the path of movement lof the projection on said disc, whereby upon rotation of said drive gear the projection thereon will engage an end of said arcuate notch to eifect rotation of said disc until the projection thereon engages sai-d fixed stop thereby restraining further rotation of -said drive gear and the shaft.

7. The combination set forth in claim 6 in which the projection on said disc is midway between the ends of fthe arcuate notch, and said fixed stop and `the projection on said drive gear are diametrically aligned when said crank bar extends at right :angles to -said parallel members.

8. The combination set forth in claim 6 in which the projection on said disc is midway between the ends of the arcuate notch, and said fixed stop and the projection on said drive gear are diametrically aligned when said crank bar extends at right Iangles to said parallel members, sai-d projections and said fixed stop each occupies 30 degrees of arc and said arcuate notch occupies more than degrees of arc, whereby said drive gear will rotate through an angle of more than degrees.

9. Drive means comprising a .pair of spaced parallel members slidably mounted for movement in unison, a drive shaft at right angles to the plane of said members, ya crank bar centrally mounted on said shaft at right angles thereto, a fpair of pins aixed respectively to each end of said crank bar and extending at right angles thereto, each of said parallel members having an associ-ated spaced outer and inner wall rigid therewith and extending from 'one end thereof toward the other end, said walls terminating before said other end to define a passageway, said pins when said crank -bar `extends at right angles to said parallel members being positioned between `the associated inner and outer walls, each of said inner walls adjacent said passageway having -an opening through which the associated pin is adapted to pas-s, whereby upon rotation of said shaft one of said pins will react against the associated inner wall to effect slidable movement of said parallel members and the other pin will be moved out of the associated opening clear of the `associated member and will thereupon be moved through the passageway in the other member to clear said other member.

No references cited. 

1. DRIVE MEANS COMPRISING A PAIR OF SPACED PARALLEL RIGIDLY CONNECTED BEAMS FORMING A FRAME MEMBER, MEANS SLIDABLY MOUNTING SAID FRAME MEMBER, A DRIVE SHAFT EXTENDING AT RIGHT ANGLES TO THE PLANE OF SAID FRAME MEMBER, A CRANK BAR MEMBER CENTRALLY MOUNTED ON SAID SHAFT AND EXTENDING AT RIGHT ANGLES THERETO, A PAIR OF DRIVE PINS CARRIED BY ONE OF SAID MEMBERS AND POSITIONED TO COACT WITH THE OTHER OF SAID MEMBERS AND MEANS TO EFFECT POSITIVE REACTION OF ONE OF SAID PINS AGAINST ONE OF THE PARALLEL MEMBERS OF SAID FRAME UPON ROTATION OF SAID DRIVE SHAFT AND MOVEMENT OF SAID CRANK BAR MEMBER FROM A POSITION AT RIGHT ANGLES TO SAID PARALLEL MEMBER OF SAID FRAME WHEREBY SAID FRAME WILL BE MOVED ALONG ITS SLIDABLE MOUNT. 